Re: [ECOS] PID ROM and eCos

[Gary Thomas <gthomas at cambridge dot redhat dot com>]

On 24-Jan-2001 Grant Edwards wrote:
> On Wed, Jan 24, 2001 at 03:15:20PM +0000, Dave Airlie wrote:
> 
>> So my question is how feasible is to build eCos for RAM, and
>> build a small routine to link against it that boots up and
>> copies all of eCos into RAM and starts it ?
> 
> Piece of cake.
> 
>> Could I use something like redboot or anything like that for
>> this purpose or is a platform where this has been done ..
> 
> Sure, RedBoot would work great, but's it's overkill if all you
> want is to copy a single fixed image to RAM and execute it.
> That only takes 10-15 lines of assembly language.
> 
> You'll probably also want to re-map memory so that RAM is at
> address 0 instead of ROM (if possible). You can run eCos from
> RAM with ROM at 0, but it's a pain since you'll have to hack up
> the vectors.S file in hal/arm/arch/.

Look at the startup code for the Cirrus Logic EDB7xxx boards.  They
support this configuration where the image in ROM (FLASH or whatever)
is linked at an address different from where they are stored.  If
this case is detected, the ROM code simply gets copied to RAM at
startup time.  Look in the file:
  hal/arm/edb7xxx/current/include/hal_platform_setup.h